The tomb cluster was discovered at a construction site in Feihu Village, Pujiang County in southwest China's Sichuan Province in September last year. It covers an area of 10,000 square metres and has 60 tombs in four rows.

As of mid-January, workers with Chengdu Cultural Relics and Archaeology Institute have excavated 47 tombs, said the institute Wednesday.

An archaeologist works on a Chuanguan boat coffin tomb[Credit: sichuan.scol.com.cn]

The tombs date back to the late Warring States Period (475 - 221 BC) and the Qin Dynasty (221-206 BC). The boat-shaped coffins are four to seven metres long and made of nanmu, a rare wood.

The cluster belonged to the indigenous Shu culture and contains elements of the Chu and Qin cultures.

Archaeologists have uncovered more than 300 pieces of pottery[Credit: sichuan.scol.com.cn]

Pujiang County was part of the Shu Kingdom, which has no written record of its history.

Workers have dug up more than 300 pieces of pottery, bronze, iron and bamboo as well as weapons, coins and 11 seals, said Gong Yangmin, head of the excavation team.

A bronze sword unearthed from one of the Chuanguan boat coffin tombs [Credit: sichuan.scol.com.cn]

Two excavated tombs were well preserved, said Gong. In one, workers discovered ten bamboo baskets of well-preserved grain and a delicate string of glass beads on the waist of the tomb owner, showing his high status.

"Glass beads like dragonfly eyes were exotic at the time. They were probably imported via the Silk Road," said Gong.

The group of tombs was discovered last September by construction workers[Credit: sichuan.scol.com.cn]

As there are ruins of salt wells nearby, the tomb owners were possibly salt administration officials, according to archaeologists.

Boat coffins have been found in Pujiang seven times. Construction work at the site has been suspended and the county government plans to build a museum there.